Houston study shows stem-cell's potential for heart treatment

Published 8:28 pm, Sunday, March 25, 2012

Houston researchers are reporting that adult stem cells have a modest benefit in younger patients with heart failure, the first large-scale evidence that the controversial yet promising new therapy can be developed to help millions of people with the disease.

In a study presented at a cardiology conference Saturday, Texas Heart Institute doctors presented results of a clinical trial showing that cells derived from patients' own bone marrow produce a small but significant increase in the heart's ability to pump oxygen-rich blood.

"This study moves us one step closer to being able to help patients with severe heart failure who lack other alternatives," said Dr. James Willerson, president of the Texas Heart Institute and the study's principal investigator. "It also points to a future in which stem cells regenerate the heart."

The study did not find improvements in a number of heart function measures, but Willerson and other study leaders said it yielded key information about the specific adult stem cells with the greatest therapeutic potential. The trial used a number of stem cell types.

Transplants limited

About 6 million people in the United States have heart failure, a progressive and eventually fatal disease in which the heart loses the ability to effectively pump sufficient amounts of blood to the body's organs. Better therapy is needed because the limited availability of donor hearts makes transplants an option for only about 2,300 people in the United States annually.

Adult stem cells have become the subject of studies for a variety of conditions - the Texas Heart Institute has many involving the heart - since laboratory research in the late 1990s showed they have the ability to grow into most any kind of tissue. This is the first intermediate-stage study in the United States, characterized by multiple centers and many dozens of patients.

The idea of therapy involving adult stem cells formerly was considered non-controversial, a more ethical alternative to destroying embryos to obtain their stem cells. But it has come under fire recently because it is increasingly being used outside of research studies and for profit, particularly in Texas, where Gov. Rick Perry received it last year for his ailing back. The unregulated activity has prompted complaints to the U.S. Food and Drug Administration and a Texas Medical Board draft policy requiring oversight for any use of experimental drugs.

3.1 percent increase

The new study, presented at an American College of Cardiology conference and to be published in the Journal of the American Medical Association, involved 92 patients at five locations - two-thirds at the Texas Heart Institute - whose hearts were pumping at less than 45 percent of capacity and could not be treated with surgery. Doctors injected patients' own stem cells or placebos into their hearts.

On average, those who received stem cells had a 3.1 percent increase in the function of their left ventricle, the heart's main pumping chamber. In contrast, the ventricle's pumping ability decreased by an average 1.6 percent in those who received placebos.

The numbers were affected by the age of patients, who averaged 63. Those 63 and older got little benefit, said Willerson, noting that research is determining that stem cells start losing the ability to grow into new tissue as people get into their sixties.

But Willerson said another Texas Heart Institute study last year found that a fat-derived primitive kind of adult stem cell, taken from one patient and transplanted in another, resulted in no rejection by the immune system - a potentially game-changing discovery. If confirmed, it could mean older adults with heart failure one day could be treated with stem cells of younger people.

'Field is maturing'

The new study found no improvement in heart damage or the heart's blood flow and oxygen use. There were no safety problems.

Study participants will continued to be followed for five years.

"Even though the benefits were modest, I think this shows the field is maturing," Willerson said. "I think we're 5 to 10 years away from approved stem cell therapies for the heart."